Infants and other incontinent individuals wear absorbent articles such as diapers to receive and contain urine and other body exudates. Absorbent articles function both to contain the discharged materials and to isolate these materials from the body of the wearer and from the wearer's garments and bed clothing. In typical diaper-like absorbent articles, the article is affixed to a wearer by wrapping front and back halves of the article about a wearer's waist and hips and attaching one or more fasteners that hold front and back halves together. Although many fasteners are known, fasteners for absorbent articles such as diapers are typically surface fasteners.
Surface fasteners, such as hook & loop type fasteners (Velcro), adhesive fasteners, and cohesive fasteners, are common in the art. These fasteners require aligning an engaging surface to a receiving surface in a face-to-face relationship and then making contact to form a reliable connection. In order for contact to be made, the engaging and receiving surfaces need to be reasonably flat or at least have generally the same shape at the time of engagement. Forces often act on such surface fasteners during engagement affecting the shape of the engaging and receiving surfaces. Such forces have a tendency to cause the engaging and receiving surfaces to buckle out of plane, commonly referred to as curling. Curling may result in at least a portion of the first surface not making good contact with the second surface at engagement, potentially compromising fastening performance in use.
Fasteners are typically attached to the diaper via some intermediate material such as a nonwoven, film, or stretch laminate forming a panel. A fastener element is typically attached inboard of the edges of the panel to provide a gripping region to facilitate fastening. Gripping regions are generally stabilized by the user's grip, but regions outboard the gripped area are subject to forces that act to bend and/or buckle the fastener element. For example, referring to a prior art fastening member depicted in FIG. 1, a user grips a fastener over length, Lg, and pulls in a lateral direction. Lateral tension, Tc, builds in the system and distributes from the gripped region through the longitudinal fastener length, Lf. Tensions along the longitudinal end edges, Te, act to bend end edges of fasteners out of plane. Tensions in the longitudinal direction, P, generated from Poisson effects (necking), act to buckle fasteners lengthwise. Shorter lengths are harder to buckle than longer lengths.
Therefore, a need exists for a fastener system capable of reducing curling during fastening. The present invention provides a fastening system that directs the majority of the forces toward the longitudinal center of a fastener element and away from the ends thereof in order to minimize distortion during fastening.